Fluid systems are ubiquitous in many industrial markets. Often these systems have pressures and/or temperatures that vary. One device useful in offsetting the expansion and contraction of fluid systems are metallic bellows accumulators. The metallic bellows accumulators allow fluid to ingress or egress to maintain a system pressure, especially in systems that experience temperature changes. For example, as temperature rises, the density of most fluids decreases causing the fluid volume to expand at a given pressure, which is generally known as Boyle's law. When temperature falls, the density of most fluids increases causing the fluid volume to contract at a given pressure. The bellows accumulators allow systems to expand and contract when temperature changes occur in a closed fluid system.
A cross sectional view of a prior art accumulator 100 is shown in FIGS. 1A and 1B. In FIG. 1A, the accumulator 100 is shown in the expanded state 102. The accumulator 100 in this construction has a housing 104 or outer shell defining a first space 106 and a bellows 108 have an end plate 109 defining a second space 110. The first space 106 is at a desired pressure and temperature. The first space 106 may be in fluid communication with a first fluid port 112 that regulates the pressure and/or temperature of the first space 106. The bellows 108 may be, for example, a welded bellows in which a number of individually formed diaphragms 114 are welded to each other along welds 116 or a formed bellows where a cylindrical tube is cold formed into a bellows. The housing 104 may be unnecessary in situations where the first space 106 is maintained at atmospheric pressures and temperatures. The second space 110 is in fluid communication with a system through a second fluid port 118. The second space 110 is generally filled with the fluid (gas or liquid). In the expanded state, as shown, the pressure of the second space 110 is greater than the pressure of the first space 106 causing the expansion of bellows 108. As can be appreciated, either of the first fluid port 112 or the second fluid port 118 can be in fluid communication with the fluid system or the regulated pressure source.
As shown in FIG. 1B, the accumulator 100 is shown in the compressed state 120. In this state, the bellows 108 is compressed, which reduces the volume of the second space 110 and increases the volume of the first space 106, which may have the effect of decreasing the pressure of the first space 106 if first space 106 is not in communication with a pressure regulation system as described above.
As the pressures in the first and second space 106, 110 change, the bellows 108 moves from a more expanded state to a more compressed state. The maximum pressure differentials occur at the compressed state 120 and the fully expanded state 102.
The bellows 108 is capable of withstanding very high pressure differentials in the compressed state 120 as the stacked bellows support each other through contact and limit the amount of deflection. The bellows 108 in the expanded state, however, are susceptible to failure. In particular, the thin metal of the bellows and the welds limit the maximum differential pressures the bellows 108 can withstand in the fully extended state as the individual diaphragms 114 do not provide significant support to adjacent diaphragms.
High pressure bellows separators, however, are desirable despite the maximum differential pressures that the bellows can withstand. Thus, a need exists in the industry for a high pressure bellows separator that can withstand significant differential pressures in the expanded state. Thus, against this background, an improved high pressure bellows separator is desirable.